Pressure responsive and indicating device



time with under inflated tires.

Patented Sept. 8, 1953 OFFICE PRESSURE RESPONSIVE AND INDICATING DEVICE Gavin W. Laurie, Springfield, Pa. Application May 18, 1950, Serial No. 162,673

4 Claims.

ThisA invention relates to a pressure indicating device, and more particularly to a pneumatic pressure responsive and indicating device adapted to indicate the pressure of pneumatic tires and the like.

It is now a generally accepted fact that: the life of a pneumatic tire on a vehicle is dependent, to a large extent, upon the air pressure within vthe tire. It is also a generally accepted fact Vthat inner tubes of pneumatic tires leak slowly and within a comparatively short period of time a pneumatic tire which had a given air pressure therein will have a reduced air pressure due to the aforementioned leak of the tube. An under 4inflated tire wears considerably faster than a tire inflated to its proper pressure.

While nearly every motorist has access to gasoline filling stations which havecompressed vair for tire inflation purposes, the average motorist does not take advantage of such tire inflation service as frequently as he should, with the result that his car is in operation over long periods of Unfortunately, the average motorist is careless about checking the air pressure in his tires to determine if they have the necessary minimum air pressure. This carelessness isattributed to the fact the motorist might soil his hands if'he checked the air pressure of his tires, coupled with the effort which he would extend and the time consumed'. Frequently the motorist will not permit the attendant to check his-tires (even if requested to do so) because, normally, the motorist is in a hurry to be on hisV way after he has purchased gasoline.

However, it is thought that if. the. motorist-could ascertain thatone or more of his tiresl was' under iniiated without the usual' problems mentioned above, he would thentake the necessary time to have the attendant inflate the particular tire or .tires which were under inflated.

The present invention has been devised to renable the/'motorist to. check the air pressure within each of his tires, without encountering any of the aforementioned problems, toy determine. if it is equal to. or above a predetermined minimum in an expeditious manner while the attendant is filling hisV automobile with gasoline.

The prime object of this invention is to provide a simple, lightweight, inexpensive device which maybe detachably secured to the valve stem of a pneumatic tire, which device may be easily' actuated manually to indicate, by sound,

sight or touch, whether or not the pressure within the tire isequal-tol'or above fa predetermined pressure.

normal position of indicator fora predetermined minimum airpres.'

sure and as a dust cap, the device being intended to. replace the customary dust caps.

Still another important object of the invention is to provide a combined pressure indicating de,- vice'-` and dust cap which may be detachably secured to the valve stemy of av pneumaticA tire, so that the device may be easily and quickly removed when it becomes necessary to add air to the tube. y

Another object4 of the invention is to provid-e a combined pressure indicating device, dustv cap, and valve stem seal to seal the air inthe tire in the event of' a leaky tire valve'.

A further objectof the invention. is to provide a; pneumatic tire pressure indicaton, dust cap and valve,- stem. seal which has relatively few moving parts. thusv eliminating wear.

Further objects and advantages of the invention will be apparent fr m the following speciiication and drawings..

Inthe drawings: i

Fi'g.V I is a vertical' section of the combined vdust cap and tire pressure indicator detachably securedf to the tire valve stem, the latter being shown in dotted. lines;

Fig. 2 is a sectional View on line 2-2 of Fig. l;

Fig'. 3' is a fragmentaryy detailed view of the audible indicating diaphragm shown in a partially depressed mid-portion, as compared to the the diaphragm as shown' in Fig;.1'; and,

Fig; 4 is a fragmentary detailed viewI of the diaphragm structure shown in the fully depressed position.

Referring now to the drawings, the combined tire pressure indicator, dust cap and valve stem seal of the present invention is provided with a spring snap diaphragm indicated by reference numeral.' In' which is normally bowed outwardly 'and is designed to be movable between two different posi-tions, the normally bowed outward positionas shown in Fig. 1'-, through the-position as shown. in Fig. 3", to the bowed inward or depressedl position as shown in Fig. 4. The diaphragm I0, which may be formed of light gauge steel or the like is constructedr so as to I no'vebe- 'y tween the two aforementioned positions with-a As the outer peripheral edge of the diaphragm,

is permanently and rigidly held to the body, the necessary absorption of the metal movement is taken up in the S-shaped wave depressions. AThe flared end of bored body cooperates with the diaphragm to provide a pressure chamber on'the underside of the diaphragm.

The central neck portion of the conical body 'member I3 is provided with an axially threaded bore I4, the latter being in communication with the axial bore of the enlarged or flared end of the device. The threaded bore I4 is also enlarged at itsinner end to provide a shoulder I5 and an enlarged threaded bore I6. The threaded bore I6 has a suitable diameter to correspond to the normal diameter of a threaded valve stem, as

indicated at Il in dotted lines. Thus, the device f .may be detachably secured to a valve stem in a manner similar to the customary dust cap. A

gasket member Iseats on the shoulder I5 to effect an air and dust tight seal between the bore of the valve'stem and the atmosphere.

An adjustable collar I9 having external threads thereon is positioned within the bore I4. The collar I9 has a centrally positioned bore 20, through which a plunger shaft or stem 2| is slidably but vnon-rotatably mounted as shown in Fig. 2. The f plunger shaft 2| is provided with an enlarged head 22 which is positioned to centrally contact the inner surface of the diaphragm I0. A compression spring 23 surrounds the periphery of the plunger shaft 2| and is positioned between t the shoulder of theenlarged head 22 and the adjustable collar I9, under compression.v

The inner end of the plunger stem 2| is notched as indicated by reference numeral 24, the notch being adapted to receive a screw driver or the like for purposes of axial adjustment of the collar I9 relative to the diaphragm, the function of which is explained in more detail hereinafter.

As previously mentioned, the outer periphery of the annular ring portion II of diaphragm III is sealed to the flared or enlarged end of the device, thus preventing egress or ingress of air or dust from the bores I4 and I5 to the atmosphere. -When the device is secured to a tire valve shown in Fig. 1, the gasket I8 prevents ingress or egress of air or dust from the valve stem to the atmos- Accordingly, the device functions as a dust cap and as a valve stem seal, should the valve 25 within the stem I1 leak.

vIn operation, the diaphragm I0 is manually -depressed by the operators thumb or linger from the position shown in Fig. l to the position as shown in Fig. 4. When such depression is accomplished the diaplnagm emanates an audible click so .as to indicate to the operator that the diaphragm has been suiiiciently depressed for pressure indicating purposes. Upon the depression ofl the diaphragm II), the plunger 2| is y moved inwardly a suicient distance to contact and depress the valve stem 25 of the tire valve within the stem I'I, thereby releasing air pressure of the tube into the bores I6 and I4 of the body I3, the pressure passing through an aperture 28 formed in the collar I9, and hence into the air tight chamber formed by the ared end of the body and the diaphragm IG. It should be noted at this point that the compression spring 23, while being weak, will urge the plunger 2| outwardly against the inner surface of the diaphragm i0 to return the diaphragm to its normal outwardly bowed position. However, the compression of the spring is insuicient to accomplish this function in and of itself and it requires the combined predetermined air pressure and spring to return the diaphragm to its normal outwardly bowed or convex position. Thus, if the air pressure within the tire enters the chamber on the under side of the diaphragm with a predetermined minimum value or more, such predetermined air pressure cooperates with the compression of the spring 23 to move the diaphragm from the manually depressed position shown in Fig. 4 to its outwardly bowed position as shown in Fig. l, and such movement emanates an audible click, which sound is of suicient intensity to be heard by the operator. The operator will know immediately that the air pressure within the tire or tube is equal to or above the minimum predetermined value. On the other hand, if the air pressure within the tire is below the minimum predetermined value, the combined forces of the air pressure on the under side of the diaphragm I0 and the compression spring 23 will be insuicient to move the diaphragm to its outer position and, accordingly, there will be no audible sound and the operator will immediately know that the pressure within the tire is below the predetermined minimum. Under such circumstances, it will be obvious that the entire device may be easily and quickly removed in the same manner as the removal of the customary' dust cap and, thereafter, the tire or tube may be pumped to the proper air pressure.

Obviously, all pneumatic tires are not intended to have the same minimum air pressure and in order to utilize the present invention to indicate diifereni; minimum air pressure values, the same may be easily adjusted by the motorist. This adjustment may be accomplished with the use of a screw driver which is applied to the notch 24 formed in the stem 2| to rotate the stem. As previously mentioned, the stem 2| is keyed in the bore 2|) of the collar I9 and hence rotation of the stem will rotate the collar through the ycooperation of the screw threads to move the collar in either direction, thereby increasing or decreasing the compression of compression spring 23. It will be obvious, of course, that if the collar I9 is moved toward the diaphragm, the compression of the spring 23 is increased so that less air pressure is needed to cooperate with the spring to force the diaphragm outwardly from its inward position and, conversely, movement of the collar I9 away1 from the diaphragm will decrease the compression of the spring 23 which in turn will necessitate a higher air pressure to cooperate with the spring to force the diaphragm outwardly.

The body I3 is preferably constructed of any suitable lightweight material, such as aluminum, aluminum alloy, plastic or the like to hold the overall weight of the device to a minimum, although it will be understood, of course, that any suitable materials may be used to construct the device consistent with the natural requirements of the various elements described.

From the foregoing description, it will be obvious that the invention disclosed herein is intended to replace the customary dust cap normally provided on the valve stem of pneumatic tires, the device functioning to act as a dust cap, valve seal and a minimum air responsive and indicating device.

I claim:

1. In combination with a valve stem having a tire valve therein, a tire pressure indicator, said indicator comprising a body having a chamber adjacent one end thereof, a snap diaphragm normally bowed outward and extending across said chamber and sealed to said body in air-tight relation closing said chamber to the atmosphere, said diaphragm being movable between an inward depressed position and a normally bowed outward position with an audible click action, the other end of said body having a threaded bore in communication with said chamber and being detachably secured to the threaded end of a tire valve stem, and a slidable plunger stem extending through said chamber and bore and having one end contacting the inner surface of said diaphragm, the other end of said stem being positioned to contact the valve stem of the tire valve when said diaphragm is moved to the depressed position to thereby release the tire air pressure to within the bore and chamber behind said diaphragm.

2. In combination with a valve stem having a tire valve therein, a tire pressure indicator, said indicator comprising a body having a chamber adjacent one end thereof, a snap diaphragm normally bowed outward and extending across said chamber and sealed to said body in air-tight relation to close said chamber to the atmosphere, said diaphragm being movable between an inward depressed position and a normally bowed outward position with a snap and audible click action, the other end of said body having a threaded bore in communication with the said chamber and being detachably secured to the threaded end of a tire valve stem, a slidable plunger stem extending through said bore and chamber and having one end contacting the inner surface of said diaphragm, the other end of said stem being positioned to contact the valve stem of the tire valve when said diaphragm is moved to the depressed position to thereby release the tire air pressure to within the bore and chamber of said body and behind said diaphragm, and a compression spring mounted within said body to normally urge said plunger and diaphragm towards the outward position.

3. In combination with a valve stem having a tire valve therein, a tire pressure indicator, said indicator comprising a body having a chamber adjacent one end thereof, a, snap diaphragm normally bowed outward and extending 'across said chamber and sealed to the body in air-tight relation to close said chamber to the atmosphere,

said diaphragm being movable between an inward depressed position and a normally bowed outward position with a snap and audible click action, the other end of said body having a threaded axial bore in communication with said chamber and being detachably secured to the threaded end of a tire valve stem, a slidable plunger stem extending through the bore and chamber of the body and having one end contacting the inner surface of said diaphragm, the other end of said stem being positioned to contact the valve stem of the tire valve when said diaphragm is moved to the depressed position to thereby release the tire air pressure to within the bore and chamber of said body and behind said diaphragm, a compression spring mounted within said body vto normally urge said plunger and diaphragm towards the outward position, and means to vary the compression of said spring.

4. In combination with a valve stem having a tire valve therein, a tire pressure indicator, said indicator comprising a body having a chamber adjacent one end thereof, a snap diaphragm normally bowed outward and extending across said chamber and sealed to the body in air-tight relation to close said chamber to the atmosphere, said diaphragm being movable between an inward depressed position and a normally bowed outward position with a snap and audible click action, the other end of said body having a threaded axial bore in communication with said chamber and being detachably secured to the threaded end of a tire valve stem, a threaded collar member mounted within the threaded bore of said body, said collar member having a bore, a slidable plunger stem slidably and non-rotatably journalled in said collar bore and having one end contacting the inner surface of said diaphragm, the other end of said stem being positioned to contact the valve stem of the tire valve when the -diaphragm is moved to the depressed position to thereby release the tire air pressure to within the bore and chamber of said body and behind said diaphragm, a compression spring tted between said collar and adjacent the end of said plunger'stem that is contacting the inner surface of said diaphragm to normally urge said diaphragm to the outward position, said stem being rotatable to rotate said threaded collar and vary the compression of said spring to thus adjust the minimum tire pressure response of the device.

GAVIN WM. LAURIE..

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date l 1,044,779 I-Iackley Nov. 19, 1912 1,548,470 Kennedy Aug. 4, 1925 1,610,452 Kennedy Dec. 14, 1926 1,618,211 McNatt Feb. 22, 1927 1,731,632 Main Oct. 15, 1929 1,846,311 Clare Feb. 23, 1932 

